#include <stdio.h>


int Mul(int a, int b)
{
    return a * b;
}

int Dif(int a, int b)
{
    return a - b;
}

int Sum(int a, int b)
{
    return a + b;
}

int main()
{
    int i = 0;
    int sum = 0;
    for(int i = 0; i <10;i++)
    {
        sum += i;
    }

    int a =10 , b =20 ;
    int ret1  = Sum(a,b);
    int ret2 = Dif(a,b);
    int ret3 = Mul(a,b);
    printf("%d\n",ret1);
    printf("%d\n",ret2);
    printf("%d\n",ret3);


    return 0;
}
